Rotary cutter.



A. LATHAM.

ROTARY GUTTER.

MTA/[S555 NVE/Wm.

UnrrED srarrpgsnijfrnnr OFFICE.

ALBERT LATHAM, 0F BEVERLY, MASSACHUSETTS, ASSIGNOR TO UNITED SHOE MACHINERY COMPANY, 0F PATERSON, NEW JERSEY, A CORPORATION OF NEW JERSEY.

ROTARY CUTTER.

Specification of Letters Patent.

Patented July 28, 1914.

To all whom it may concern:

Be it. known that I, ,ALBERT LATHAM, a citizen of the United States, residing at Beverly, in the county of Essex and State of Massachusetts, have invented certain Imrovements in Rotary Cutters, of which the ollowing description, in connection 'with the accompanying drawings, is a specification, like reference characters on ings indicating like part-s in the several figures.

This'inrention relates to rotary cutters of the type used in the manufacture of boots and shoes for the purpose of trimming the ed es of the soles.

he invention aims particularly to overcome certain defects that have been encountered in using the cutters of the common commercial constructions.

For the purpose of explaining these objects more clearly, a cutter made in accordance with the usual methods has been shown in end and side elevations, respectively, in Figures l and 2 of the accompanying drawcuter of this type is mounted for use on the enc` of a'rotary shaft which is driven at a v y high speed, usually about SOQO revolutions per minute; and the shoe is guided for the operation of the cutter on the sole edge entirely by the hands of the work man. This trimming operation gives to the sole edge its final shape and determines the relation of the sole edge `to the upper of the shoe. Consequently it determines, to a considerable extent, the style of the shoe. The proper guiding 0f the shoe for the trimming operation requires great care and skill on the part of the workmanv since the cutter trims very rapidly and any variation from an accurate guiding movement of the shoe may cause the cutter to trim into the sole edge too deeply or even into the upper, in which case the shoe will be rendere unsalable.

The cutter imparts to the sole edge-in the trimming operation a transverse contour that is a complement of the transverse contour of the cutter; and for many purposes a cutter is employed that is larger at one end than at the other so as to give to the edge of the sole a rounded or beveled shape. A cutter of this character is shown in Figs. 1 and 2; and such a cutter is used in the majority of cases in'trimming the shank porl tien of the sole edge of a shoe.

the draw-- For this reason a cutter of the general style shown in l and is commonly known to the trade as a shank cutter. This cutter is slotted in the usual manner in a direction parallel to the axis of the cutter and in such a manner that the front face a of each tooth furnis an acute angle with a radial plane of the cutter; in otl1ei'\vords, this face lies in a plane 'tangent to a cylinder lyin within the cutter and coaxial therewith. ln using a cutter o1 this construction it is found that the part oi the edge of each tooth at the large end of the cutter begins to cut before the part of the edge at the small end of the cutter, due to the fact that the part of the cutting edge at the large end lies in a plane that is angulnrly in advance of the part of the cutting edge at the small end of the cutter. This relationship will be understoodfrom an vinspection of F ig. l, in vwhich the lines .7i and c indicate, respectively, the radial planes of the portions of the cutting edge at. the extreme ends of the tooth A.-

The effect of this characteristic of a cutter oi this style is to crowd the sole toward the small end of the cutter. This crowding action must, of course, be counteracted by the Workman if he is to trim the sole ed e properly, and it reatly increases the di culty of guiding t e shoe accurately for this operation.` A further objection to which cutters of this character are open is the fact that the inclined part of the cutting edge of each tooth has much less clearance than the part lying more nearly parallel to the axis oi the cutter. Clearance is obtained either by backing-off the teeth, as in the construction shown in Figs. 1 and :2, or else by tipping back each `tooth; but the same objection is present whichever method is employed. In the backing-olf operation the cutter is rotated on its axis While the backingb tool is fed against each tooth in such a manner that it takes, at iirst, only a small shaving` from the back of the peripheral face oi' each tooth. The tool is then moved .slightly farther toward the axis of the cutter so that it takes oil' a longer shaving and this feeding movement is continued until the tool finally takes a shaving ofi the entire circumferential length of each tooth; the result beingr that the tooth is made much lower at its back edge than at its front or cutting edge. Since, however, the feeding motion of the backing-oil' tool is radial of the cutter it obviously Will give to each tooth a considerably reater clearance at the part of the bed o? the cutter indicated, for instance, at d, Fig. 2, than at the part indicated at e, Fig. 2, Where the peripheral face of the tooth extends in a direction nearly parallel to the direction of the feeding movement of the backing-off tool. The part of the cutter at e, therefore, will not cut nearly as freely as will the part at d and it will exert more of a draggin and rubbing action on the work than willy'the part at al. Sometimes his rubn bing action is sutlicient to burn, or slightly discolor7 the stock; and it always adds an element of resistance to the guiding movement that the operator must give to the shoe in order to cause the cutter to trim the sole, and thus makes the proper guiding of the shoe more difficult. The present invention is concerned particularly with overcoming these defects.

A convenient embodiment of the invention will now be described and the manner in which it is proposed to overcome these defects will be explained, rei\rence being made to the remaining views of the drawi s, in Whichigs. 3 and 4 show in end and side elevation, respectively, a cutter blank; Figs. 5 and 6 are plan and end views, respectively, of the cutter blank showing the manner in which the slotting or milling operation is performed; Figs. 7 and 8 are plan and end views, respectively, showing the manner in which the cutter is backed off; and Figs. 9 and 10 are end and side views, respectively, of the completed'cutter.

The cutter blank indicated at 2 in Figs. 3 and 4 is made in the usual manner, the periphery of this cutter being given a transverse contour which is. the complement of the contour that it is desired to impart to the edge of the shoe sole. According to the .referred method of procedure, this cutter lank is next slotted. This operation is usuali erformed in a milling machine, the b an being clamped on a suitable spindle, and a' milling cutter 4 of appropriate shape being provided, the milling cut ter and blank then being moved relatively to each other to cause the cutter to form slots of appropriate depth and at the proper distance apart in the blank 2. This operation, of course, forms the circumferential series of teeth of the cutter. The usual form of milling cutter may be employed for his purpose but, instead of slotting the blaii .'f in a direction parallel to its axis, which is the procedure usuallv followed, the slotting is done at a slight angle to the axis of the cutter, as indicated clearly in Fig. 5. ln other words, the milling cutter l usually is set with its axis at right angles to the axis of the blank 2 and is fed through the blank in a direction parallel to the plane of rotation of the cutter; while in the present case the axis o'l' the milling cutter 4 is swung in a counter-clockwise direction with reference to the axis of the blank 2 as the parts are seen in Fig. 5, until they come into about the relationship there shown and the milling cutter is then fed through the blank 2 in a direction parallel to its plane of rotation. Usually the milling cutter 4 is fed through the blank 2 until the center ot the cutter has passed beyond the back of the blank; but it is preferable in many cases in forming the cutters of this invention to stop the feed of the milling cutter when its center has just passed the lip f of the blank so that the back of the cutter wili not be slotted as deeply, and consequently will be stronger than it would be otherwise. Acutter slotted in this manner instead of having the front face o of cach tooth lying in a plane tangent to a` cylinder Within the cutter, as in Fig. l, will have the front face of each tooth lying in a plane tangent to a cone extending coaxially through the cutter With its base at the large end of the cutter. The effect of this operation is to swing the angular position of that portion of the cuttin edge of each tooth at the large end of t e cutter backwardly with relation to the cutting edge at the small end of the cutter by an amount depending upon the angle at which the slotting is done. The relation of the angle of the slotting to the extreme difference in radial dimensions of the ends of the cutter may be made such that the end portions of the cutting edge of each tooth will be brought into the same radial plane. This is the case in the completed cutter shown in Figs. 9 and l()1 in which the line :v indicates a radial plane of the cutter and the points of the cutting edge of the tooth B at its opposite ends lie in the plane m-. inasmuch as the 'transverse contour ofthe cutter shown is a curve, the portion of the cutting edge of the bed of the tooth between the ends does not lie in the plane .fc-av; but if this part of the cutter Were straight, then the entire cutting edge of the bed of the tooth would lie in the plane It is obvious that, if exactly this relationship were to be obtained for every change in the maximum and minimum dis tant-es of the ends of the cutting edge of each tooth from the axis of the cutter, it would be necessary to vary the angle of the slotting for each variation in this difference; but inasmuch as this difference, in styles of vcutters most commonly used, is confined within relatively narrow limits, it is pos sible to adopt a mean angle of slotting that will be satisfactory for all of these more common styles. I have found from ex pcrience that. an angle of l5 degrees meets these requirements; that is, when these action on the Work which has been above del scribed in .discussing the present commercial. cutters, since the end portions of the cutting edge of each tooth begin to cut at substantially the same instant and the cutter does not, therefore, tend t0 crowd the sole in either direction axially of the cutter.

In determining the angle at Which the slotting shall be done, the lip f of the-cutter may usually be disregarded since this part of the cutter does not perform suflicient Work to affect appreciably the result that is sought, and since 1n the more usual styles of cutters, as in the cutter shown in Figs. 9 and l0, if the angle of slotting is determined with reference to the bed of the cutter, the cutting edge of the lip of each tooth will lie substantially in the radial plane of the ends of the cutting edge of the bed of the tooth. In

most instances, as in the cutter shown, the

l struction avoids the rabbino and drin angle is determined with reference to the maximum and minimum distances of Ithe portions of the cutting edge of the bed of the tooth from the axis of the cutter. But it is obvious that, in manufacturing special styles of cutters in which the lip does perform a considerable part of the Work, the angle of milling can be adjusted onv the principle above indicated so that the end of the cuttingr edge of the lip shall be brought into the same radial plane as the opposite end of the edge of the tootii.

The cutter, as it comes from the milling machine after being slotted, preferably is given a clearance by backingol. This operation may be performed in a backing-oli" machine and by means of a backing-of`f tool 6, Figs. 7 and 8, of the usual construction. According to the present invention, however, the backing-olf tool, instead of being fed radially ofitli'e cutteras usual, is fed at a.

slight angleY to the radius of the cutter, as indicated in Fig. P(,this angle being such that the main component of the feeding motion is toward the axis of the cutter, while a smaller component is directed parallel to the axis of the cutter and toward the back or larger end of the cutter. The result is to remove the metal from behind the cutting edge of each tooth in a lateral direction as Well as in a radial direction and, consequently, to give the cutter not only the usual radial clearance but also a slight lateral clearanceY This ii u, is usuali iarplv i action that, as above staf which the backing-olf operation isperformed may be varied as conditions require, but for the more common styles of cutters an angle of about l5 degrees is found satisfactory. This angle lies in a radial plane of the cutter and is measured from a radius of the cutter. The result just described might also be obtained by backing-olf the cutter in the usual manner and then giving it a slight lateral backing-olf, but the first named method is preferred since it leaves the peripheral face of each tooth of thecutter in such shape that its transverse contour will not be changed as it is ground backwardly for the purpose of sharpening the cutter. In the latter method, the lip of the cutter will be of uniform thickness from front to back 'so that a slight change in transverse contour would take place as the tooth became thinner after repeated shapenings. Theclearance of the lip is practical* as great inthe former case as in the latter, since its surface recedes toward the asis of the cutter so rapidly behind the cutting edge that only a small part of its length comes in contact with the work and the laterai increase in thickness of this'part of the lip is not sufHcient to be appreciable.

The elimination of the crowding and rubhing actions above .described inv discussing the y'previous types of commercial cutters materially reduces the eifort necessary to guide a shoe properly for the trimming operation and it eliminates the discoloring or burning action that previously has given trouble in using cutters of this general type.

Having thus described my invention, what I claim as new and desire to secure by Letters Pat/ent of the United States is 1. A rotary cutter of the character` described having a plurality of teeth arranged in a circumferential series, the cutting edge of each tooth comprising portions lying at different radial distances from the axis of the cutter and having (portions of said edge lying at maximum an minimum distances from said axis in substantially the same radial plane, the front face of each tooth 2. A rotary edge trimming cutter larger at one end than at the other and havin a plurality of teeth arranged in a circum erential series, said cutter having slots separating adjacent teeth, the fron'tvface ofeach tooth lying in a plane tangent to the surface of a cone extending eoaxially'throu h thevcutter with its base at the larger en of the cut ter, and the port-ions of the cutting edge o5 each tooth at its opposite ends lying in sub stantially the same radial plane.

3. A rotary edge trimming cutter havin a plurality of teeth arranged in a circum ferent-iai series, each of said teeth havin f the ends of the cutting edge of its bed didierent distances from the axis the cutter and lying 1n substantially t e same radial plane, and being so shaped that its front face extends at an acute angle to said plane.

4. A rotar edge trimming cutter larger at one end t an at the other and havin a plurality of teeth arranged in a circum erential series2 said cutter being slotted at such an angle with relation to its axis that the portions of the cutting edge of each tooth at its opposite ends lie in substantially the same radial plane, while the front face of each tooth extendsat an acute angle to said plane, and the teeth of said cutter being backed ofi' both laterally and radially.

5. A rotary edge trimming cutter having a plurality of teeth arranged in a circumferential series, the cuttin edge of each tooth comprising portions dying at diferent radial distances from the axis of the cutter, and each tooth being so shaped that its cutting edge has both lateral and radial clearance.

6. A rotary edge trimming cutter having a plurality of teeth arran ed in circumferential series, the cutting e ge of each tooth comprising'portions lying at different radial distances from the axis of the cutter, each tooth having both lateral and radial clearance but being so shaped that the transverse contour of its peripheral face will not be changed by the sharpening operations.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

' ALBERT* LATI-IAM.

Witnesses: l

NORMAN C. HUssEY, JOHN H. MCCREADY. 

